1. Field of Disclosure
The present disclosure relates to the stereo image display, especially for the stereo image display applied with shutter glasses.
2. Description of Related Art
As known in the art, when two eyes looks at two images with a parallax, according to the visual function of human eye, the two image can form a stereo image in visual effect. In order to produce the stereo visual effect to the viewer when looking at the images displayed on the display panel, several mechanisms have been proposed. One of the displaying mechanisms for stereo visual effect is based on time multiplexed mechanism. Taking left eye and right eye for descriptions, a display panel can display a left-eye image and a right-eye image in a short time sequence. The left-eye image and the right-eye image have the same object content but with a parallax. By help of a specific eyeglass, the left-eye image and the right-eye image are separately entering the left eye and the right eye. Due to persistence of vision, the left-eye image and the right-eye image form a stereo image in visual effect.
For the specific eyeglasses to view the stereo image, its need to be design to respectively transmit the left-eye image and the right-eye image to the left eye and the right eye. FIG. 1 is a drawing, schematically illustrating a conventional shutter eyeglasses. In FIG. 1, a shutter eyeglasses 100 has a left-eye glass 102 indicated by L and a right-eye glass 104 indicated by R. The shutter eyeglasses 100 is for example a liquid crystal (LC) shutter eyeglasses. Due to the control of the LC, the glasses become transparent to the light or blocking the light. Under control, in one case, the left-eye glass 102 is switched to an open state for transmitting light while the right-eye glass 104 is closed for blocking the light, indicated by hatched pattern. As a result, the left-eye image can be viewed by, the left eye of the user. Likewise, when the right-eye image is to be received by the right-eye glass of the user, the left-eye glass 102 is closed for blocking the light while the right-eye glass 104 is switched to the open state for transmitting the right-eye image. The switching frequency can be 120 Hz, 240 Hz, 480 Hz, or higher, depending on the actual capability. Also, other type of shutter eyeglass can also be used.
FIG. 2 is a drawing schematically illustrating the mechanism to produce the stereo visual effect. In FIG. 2, the upper signal indicated by L-eye is the timing of open/close states for the left-eye glass, the lower signal indicated by R-eye is the timing of open/close states for the right-eye glass. In this situation, when the right-eye glass is close, the left-eye is open. Likewise, when the left-eye glass is close, the right-eye is open. When the right-eye image is to be transmitted by the left-eye glass, the LCD should display the R-image to replace the L-image at the previous image frame. In other words, the L-image is update by the R-image. When the time goes to the next image frame or the next time period for displaying the L-image in new image field, the left-eye glass is open and the right-eye glass is close. The LCD starts to update the displayed image of previous R-image with the L-image. The L-image and the R-image form the stereo visual effect in human visual function.
In a more recently development, since the displaying speed of the LCD is sufficiently fast, such as up to 480 Hz or even higher, the display system allows multiple users to individually view the different stereo images. FIG. 3 is a drawing, schematically illustrating a conventional display mechanism for four viewers. In FIG. 3, eight image frames are displayed by the screen of LCD panel. It should be noted that the conventional method generates the images for multiple viewers one at a time. The shutter eyeglasses for the viewer is also switched on one at a time. The first pair of two image frames is left frame and right frame for the viewer A. The second pair of two image frames is left frame and right frame for the viewer B. The third pair of two image frames is left frame and right frame for the viewer C. The fourth pair of two image frames is left frame and right frame for the viewer D. Each pair of two image frames may be all different or the same. However, different viewers would view the different specific image frames due the timing control of the shutter eyeglass in FIG. 1.
FIG. 4 is a drawing, schematically illustrating a conventional time control for four viewers to view four stereo images. In FIG. 4, the signal A represents the time period for the viewer A to view one individual image. The time period for the viewer A occupy two sub periods 120 and 121 for displaying the left-eye image and right-eye image. The shutter eyeglasses are controlled as indicated by the four groups of signals including L signal and R signal. It can be seen that the two eyes for the viewer are consecutively receiving the left eye image and right eye image. Then, this viewer has to wait for a long time to see the next image frame until all other viewers have also seen the current image frame. In other words, the left image and the right image are not symmetrically or periodically enter the left eye and the right eye of one viewer.
The conventional method to display the stereo visual image may cause uncomfortable to the eyes.